The invention is in the field of multiple photoflash lamp units, such as planar arrays.
The above-referenced patent applications disclose multiple flash lamp units that can be connected to a camera in different orientations in each of which a different group of the flash lamps is relatively farther from the camera lens axis than are the other lamps of the unit. The lamps and electrical circuitry are arranged so that in any of the orientations of the unit with respect to the camera, only the group of lamps relatively farther from the lens axis can be flashed. The purpose of such an arrangement is to position the "active" group of flash lamps farther above the camera lens in order to reduce the possibility of a "red-eye" effect that causes the pupils of a person's eyes to appear red or pink in flash pictures taken when the flash lamp is close to the camera lens.
Each of the first six above-referenced multiple flash lamp arrays has, in a preferred embodiment, a circuit board having integral plug-in connector tabs each provided with a plurality of electrical connection terminals in the form of conductive stripes printed on or otherwise attached to the connector tab. The various connector terminals are connected to individual lamps or to sequential firing circuitry carried on the circuit board and interconnected with lamps in the unit. The sequential firing circuitry includes radiation-actuated switches respectively positioned near the lamps (except the last lamp to be flashed), and these switches respond to radiation (heat and light) from an adjacent flashing lamp and connect the next to be flashed lamp into the circuit so that it will be flashed next. The flash arrays have flash indicators in the form of colored areas respectively adjacent the lamps, which are visible from the rear of the array and they change color in response to radiation from an adjacent flashing lamp, thus indicating at a glance which lamps have been flashed and which have not been flashed.
U.S. Pat. No. 3,458,270 to Ganser describes a flash array having radiation-activated switches in a sequencing circuit.